1448-Count-Good-Nodes-in-Binary-Tree.java

class Solution {

    public int goodNodes(TreeNode root) {
        return helper(root, -99999);
    }

    public int helper(TreeNode root, int max) {
        if (root == null) return 0;

        int res = root.val >= max ? 1 : 0;

        res += helper(root.left, Math.max(root.val, max));
        res += helper(root.right, Math.max(root.val, max));

        return res;
    }
}